task2 finished

kernel/sysproc.c

@@ -123,3 +123,41 @@ sys_uptime(void)
   release(&tickslock);
   return xticks;
 }
+
+uint64
+sys_pgaccess(void)
+{
+  uint64 va;
+  int n;
+  uint64 user_mask_addr;
+  argaddr(0, &va);
+  argint(1, &n);
+  argaddr(2, &user_mask_addr);
+  if (va < 0 || n < 0 || user_mask_addr < 0)
+    return -1;
+
+  if (n < 0 || n > 32)
+    return -1;
+
+  struct proc *p = myproc();
+  uint64 mask = 0;
+
+  for (int i = 0; i < n; i++) {
+    uint64 v = va + i * PGSIZE;
+    pte_t *pte = walk(p->pagetable, v, 0);
+
+    if (!pte || (*pte & PTE_PS))
+      continue;
+
+    if ((*pte & PTE_V) && (*pte & PTE_A)) {
+      mask |= (1 << i);       // Set bit i in mask
+      *pte &= ~PTE_A;         // Clear the Accessed bit
+    }
+  }
+
+  if (copyout(p->pagetable, user_mask_addr, (char*)&mask, sizeof(mask)) < 0)
+    return -1;
+
+  return 0;
+}
+